During vaginal delivery, the delivery requires the fetal head to mold to accommodate the geometric constraints of the birth canal. Excessive molding can produce brain injuries and long-term sequelae. Understanding the loading of the fetal brain during the second stage of labor (fully dilated cervix, active pushing, and expulsion of fetus) could thus help predict the safety of the newborn during vaginal delivery. To this end, this study proposes a finite element model of the fetal head and maternal canal environment that is capable of predicting the stresses experienced by the fetal brain at the onset of the second phase of labor. Both fetal and maternal models were adapted from existing studies to represent the geometry of full-term pregnancy. Two fetal positions were compared: left-occiput-anterior and left-occiput-posterior. The results demonstrate that left-occiput-anterior position reduces the maternal tissue deformation, at the cost of higher stress in the fetal brain. In both cases, stress is concentrated underneath the sutures, though the location varies depending on the presentation. In summary, this study provides a patient-specific simulation platform for the study of vaginal delivery and its effect on both the fetal brain and maternal anatomy. Finally, it is suggested that such an approach has the potential to be used by obstetricians to support their decision-making processes through the simulation of various delivery scenarios.

BACKGROUND: It remains unclear whether balance is influenced by biological sex, anthropometrics, wearing footwear, or dual tasking. Such information is important to aid clinical reasoning pertaining to assessment and rehabilitation. OBJECTIVE: To investigate the influence of biological sex, anthropometrics, footwear, physical activity and dual tasking (DT) on balance performance. METHODS: An observational study was performed on eighty-six healthy participants. Anthropometric assessment and static balance performance was evaluated, during double leg stance with eyes open (DLSEO) and eyes closed (DLSEC) and during single-leg-stance (SLS). All tasks were assessed with and without footwear and a cognitive task was introduced to assess the effect of DT on static balance performance. RESULTS: Generally, the static balance performance of females was better than males, across all balance tasks, with some large effect sizes (ES). In both sexes, without footwear tasks resulted in better balance during the DLSEC task but with footwear, static balance performance was better during SLS in males only. Overall minimal differences were observed between single and dual task with a large ES for SLS and DLSEO for females. Upper body size was moderately negatively correlated to static balance performance. CONCLUSION: Females outperformed males, footwear and DT had some, but minimal influence on static balance. Anthropometrics were moderately correlated with balance. Balance performance should be compared to unisex normative data sets and performed as a single task, with or without footwear.

BACKGROUND:Despite wobble board use being common in physiotherapy the effect of certain factors, essential to clinical reasoning, have not been investigated.OBJECTIVE:To determine the effect of biological sex, anthropometrics, footwear and dual tasking (DT) on wobble board balance performance.METHODS:Eighty-six healthy participants (44 females) had their wobble board performance measured during double-leg-stance (DLS) with eyes open (DLSEO), closed (DLSEC) and single-leg-stance (SLS) tasks, with and without footwear and a DT added. Anthropometrics were also measured.RESULTS:Females outperformed males during most tasks, with some large effect sizes (ES). Performance was moderately related to weight and shoulder, waist and hip circumference. Overall, there were no differences between footwear and no footwear, except for males during SLS. DT made little difference, except during DLSEO and SLS, where single task was better than DT, though only females had a large ES.CONCLUSION:During wobble board tasks, biological sex differences were observed and a modest correlation between anthropometrics and performance noted. DT and footwear had minimal effect.

This study presents car crash-induced neck injury trends in response to variations in three impact variables: velocity (10 - 45 mph; 16.1 - 72.4 km/h), location (front, rear, near side, and far side), and angle (-45 degrees to 45 degrees). By employing a combined finite element (FE)-mathematical surrogate modeling approach, the number of necessary FE crash simulations was significantly reduced. Each motor vehicle collision (MVC) case was simulated with LS-DYNA software, and the extracted neck injury metrics (Nij, Nkm, and Lateral Nij) were used to train Kriging surrogate models. These models produced clear response trends indicating that increased impact velocity and locational proximity to the driver often resulted in the greatest risk of inducing neck injury. Further, the impact angle variable typically produced the greatest risk under direct or slightly oblique angles regardless of the impact location or whether the impact was directed toward the occupant. This lack of interaction between the angle and location variables was likely caused by limitations within the injury metrics, themselves, which do not account for multi-axial or oblique loading, highlighting the need for improved metrics. Finally, distinct pairings of sub-metric component responses were noted in most impact scenarios. These trends may be a signifier for the primary modality of injury and should be assessed in a future study.

Background: Falls are a common and costly problem, with poor balance a significant contributor. Wobble boards are commonly used for balance enhancement. However, the efficacy of wobble board training is not well understood, particularly in the older adult. Objectives: To appraise and synthesise literature pertaining to the effect of wobble board training on balance in older adults. Methods: A systematic search of Medline, Scopus, EBSCO, CINAHL, Science Direct, and Google Scholar databases was conducted up to August 2020. Articles comparing balance before and after wobble board training were included and quality appraised using the modified Downs and Black checklist. Results: Six relevant studies (n = 129) were identified for review: four randomised-controlled-trials, one pilot-study and one repeated-measures design. The overall weighted average percentages, calculated from those studies where possible suggested an improvement in Berg Balance Scale (or similar) was 4.4% and for timed-up and go, 6.3%. Mean effect sizes ranged from 0.09 to 0.96. Overall, there is conflicting evidence to support wobble training for balance improvement in older adults. Magnitude of real change was often small questioning the impact of such small improvements on overall balance function. Effect sizes for balance enhancement through wobble board training were modest, with the largest effects on multi-modal balance outcome measures, such as the Berg Balance Scale. The results indicate that if wobble board programmes are simple and of a sufficient 'within session' duration, then some improvements in balance can be demonstrated within 3-weeks. Conclusions: The evidence suggests conflicting results for the improvement of balance with wobble board training in older adults. Where effects were seen their magnitude was modest. Future studies should focus on determining the optimal wobble board programme to enhance balance.

Background Performing high-quality chest compressions during cardiopulmonary resuscitation (CPR) requires achieving of a target depth, release force, rate and duty cycle. Objective This study evaluates whether ‘real time’ feedback could improve infant CPR performance in basic life support-trained (BLS) and lay rescuers. It also investigates whether delivering rescue breaths hinders performing high-quality chest compressions. Also, this study reports raw data from the two methods used to calculate duty cycle performance. Methodology BLS (n=28) and lay (n=38) rescuers were randomly allocated to respective ‘feedback’ or ‘no-feedback’ groups, to perform two-thumb chest compressions on an instrumented infant manikin. Chest compression performance was then investigated across three compression algorithms (compression only; five rescue breaths then compression only; five rescue breaths then 15:2 compressions). Two different routes to calculate duty cycle were also investigated, due to conflicting instruction in the literature. Results No-feedback BLS and lay groups demonstrated <3% compliance against each performance target. The feedback rescuers produced 20-fold and 10-fold increases in BLS and lay cohorts, respectively, achieving all targets concurrently in >60% and >25% of all chest compressions, across all three algorithms. Performing rescue breaths did not impede chest compression quality. Conclusions A feedback system has great potential to improve infant CPR performance, especially in cohorts that have an underlying understanding of the technique. The addition of rescue breaths—a potential distraction—did not negatively influence chest compression quality. Duty cycle performance depended on the calculation method, meaning there is an urgent requirement to agree a single measure.

Head injury in childhood is the most common cause of death or permanent disability from injury. However, insufficient understanding exists of the response of a child's head to injurious loading scenarios to establish cause and effect relationships to assist forensic and safetly investigations. Largely as a result of a lack of availability of paediatric clinical and Post-Mortem-Human-Surrogate (PMHS) experimental data, a new approach to infant head injury experimentation has been developed. A coupled-methodology, combining a physical infant head surrogate, producing "real world" global, regional and localised impact response data and a computational Finite-Element (FE-head) model was created and validated against available PMHS and physical model global impact response data. Experimental impact simulations were performed to investigate regional and localised injury vulnerability. Different regions of the head produced accelerations significantly greater than those calculated using the currently available method of measuring the global, whole head response. The majority of material strain was produced within the relatively elastic suture and fontanelle regions, rather than the skull bones. A subsequent parametric analysis was conducted to provide a correlation between fall height and areas of maximum-stress-response and fracture-risk-probability. The FE-head was further applied to investigating fracture risk, simulating injurious PMHS impacts and a good qualitative match was observed. The FE-head shows significant potential for the study of infant head injury and is anticipated to be a motivating tool for the improvement of head injury understanding across a range of potentially injurious head loading scenarios.

AIM:Surface tribological properties of a tendon in terms of coefficient of friction and lubrication mechanism are expected to change with the progression of surface tears which can affect the optimal function of the tendon. This study investigated whether coefficient of friction proportionally increases with the progression of a surface tear in a bovine tendon model.METHODS:The study was performed using a pin-on-glass tribometer and bovine tendon samples (n = 16) divided into 4 groups. One group of tendons had no surface tears and thus served as a control, whilst the other 3 groups comprised tendons with increasing severity of artificially-induced surface tears. The coefficient of friction and the lubrication mechanism of the four groups of samples were investigated, calculated and compared.RESULTS:Statistical analysis showed significant change in coefficient of friction between the control group and the group with minimal tear (p < 0.05) while no difference noted between the groups of moderate to severe tear suggesting that the coefficient of friction increases initially with appearance of surface tears, though further progression to a significant tear do not cause a further increase in the frictional coefficient. There was no change in the lubrication mechanism between the groups.CONCLUSION:This finding appears to contradict the speculation that the frictional coefficient continues to increase with an increase in surface tear severity. The finding has not been reported before and requires validation in future with testing in human tissue.

Neonatal heart disorders represent a major clinical challenge, with congenital heart disease alone affecting 36,000 new-borns annually within the European Union. Surgical intervention to restore normal function includes the implantation of synthetic and biological materials; however, a lack of experimental data describing the mechanical behaviour of neonatal cardiac tissue is likely to contribute to the relatively poor short- and long-term outcome of these implants. This study focused on characterising the mechanical behaviour of neonatal cardiac tissue using a porcine model, to enhance the understanding of how this differs to the equivalent mature tissue. The biomechanical properties of neonatal porcine cardiac tissue were characterised by uniaxial tensile, biaxial tensile, and simple shear loading modes, using samples collected from the anterior and posterior walls of the right and left ventricles. Histological images were prepared using Masson's trichrome staining, to enable assessment of the microstructure and correlation with tissue behaviour. The mechanical tests demonstrated that the neonatal cardiac tissue is non linear, anisotropic, viscoelastic and heterogeneous. Our data provide a baseline describing the biomechanical behaviour of immature porcine cardiac tissue. Comparison with published data also indicated that the neonatal porcine cardiac tissue exhibits one-half the stiffness of mature porcine tissue in uniaxial extension testing, one-third in biaxial extension testing, and one-fourth stiffness in simple shear testing; hence, it provides an indication as to the relative change in characteristics associated with tissue maturation. These data may prove valuable to researchers investigating neonatal cardiac mechanics.

Head injury in childhood is a common cause of death or permanent disability from injury. However, despite its frequency and significance, there is little understanding of how a child’s head responds during injurious loading. Whilst Infant Post Mortem Human Subject (PMHS) experimentation is a logical approach to understand injury biomechanics, it is the authors’ opinion that a lack of subject availability is hindering potential progress. Computer modelling adds great value when considering adult populations; however, its potential remains largely untapped for infant surrogates. The complexities of child growth and development, which result in age dependent changes in anatomy, geometry and physical response characteristics, present new challenges for computational simulation. Further geometric challenges are presented by the intricate infant cranial bones, which are separated by sutures and fontanelles and demonstrate a visible fibre orientation. This study presents an FE model of a newborn infant’s head, developed from high-resolution computer tomography scans, informed by published tissue material properties. To mimic the fibre orientation of immature cranial bone, anisotropic properties were applied to the FE cranial bone model, with elastic moduli representing the bone response both parallel and perpendicular to the fibre orientation. Biofiedility of the computational model was confirmed by global validation against published PMHS data, by replicating experimental impact tests with a series of computational simulations, in terms of head kinematic responses. Numerical results confirm that the FE head model’s mechanical response is in favourable agreement with the PMHS drop test results. Keywords—Finite element analysis, impact simulation, infant head trauma, material properties, post mortem human subjects.

BACKGROUND:Scrummaging is unique to rugby union and involves 2 'packs' of 8 players competing to regain ball possession. Intending to serve as a quick and safe method to restart the game, injury prevalence during scrummaging necessitates further evaluation of this environment.AIMS:The aim of this study was to determine the effect of scrummage engagement sequences on spinal kinematics of the hooker. The conditions investigated were: (1) live competitive scrummaging using the new 'crouch, bind, set' sequence; (2) live competitive scrummaging using the old 'crouch touch pause engage' sequence and (3) training scrummaging using a scrum machine.METHODS:Inertial sensors provided three-dimensional kinematic data across 5 spinal regions. Participants (n=29) were adult, male community club and university-level hookers.RESULTS:Engagement sequence had no effect on resultant kinematics of any spinal region. Machine scrummaging resulted in lesser magnitudes of motion in the upper spinal regions. Around two-thirds of the total available cervical motion was utilised during live scrummaging.CONCLUSIONS:This study indicates that the most recent laws do not influence the spinal kinematics of the hooker during live scrummaging; however, there may be other benefits from these law changes that fall outside the scope of this investigation.

Artificial surfaces are now an established alternative to grass (natural) surfaces in rugby union. Little is known, however, about their potential to reduce injury. This study characterises the spinal kinematics of rugby union hookers during scrummaging on third-generation synthetic (3G) and natural pitches. The spine was sectioned into five segments, with inertial sensors providing three-dimensional kinematic data sampled at 40Hz/sensor. Twenty-two adult, male community club and university-level hookers were recruited. An equal number were analysed whilst scrummaging on natural or synthetic turf. Players scrummaging on synthetic turf demonstrated less angular velocity in the lower thoracic spine for right and left lateral bending and right rotation. The general reduction in the range of motion and velocities, extrapolated over a prolonged playing career, may mean that the synthetic turf could result in fewer degenerative injuries. It should be noted, however, that this conclusion considers only the scrummaging scenario.

Presented is the development of a simulation that allows for preliminary investigation of impact to a 10 day old infant head. A computer-aided drafting (CAD) model is reconstructed from high resolution computerised tomography (CT) scan images and meshed for finite element analysis (FEA); soft tissue responses were defined using recently derived material properties. It is anticipated that the FE model will be used to investigate the paediatric head response during impact conditions, to provide a better understanding/prediction of injury biomechanics.

BACKGROUND: The relationship between muscular force and electromyography (EMG) has been investigated by numerous researchers. EMG has not previously been used as a means of estimating force in the cervical erector spinae (CES). OBJECTIVE: Use EMG of the CES musculature to indirectly predict neck e xtension force. METHODS: Isometric contractions of the CES muscles were studied at increasing levels of contractile force across all participants (n= 12) to produce an individualised force-EMG relationship. The method of least squares was used to determine the linear regression trend line for the force-EMG relationship. The validity of these individual `correlation curves' was demonstrated through further, blinded, investigation. RESULTS: A linear relationship was identified for the individualised correlation curves that gained in strength for < 50% maximum voluntary contraction (MVC; R2> 0.8 for 80% of trials). The prediction of muscle force from the correlation curves was found to be statistically similar to the equivalent experimental data (p> 0.05). Given the tendency of EMG to slightly overestimate force in most cases, an adjustment coefficient was calculated to reduce the error in the predicted force data. CONCLUSIONS: This study reports a validated method using EMG to indirectly acquire CES muscular force, which has application for clinicians and research scientists working in fields including sport and rehabilitation.

OBJECTIVES:The purpose of this study was to investigate the reliability of a novel motion analysis device for measuring the regional breakdown of spinal motion and describing the relative motion of different segments of the thoracolumbar (TL) spine. METHODS:Two protocols were applied to 18 healthy participants. In protocol 1, 2 sensors were placed on the forehead and T1 to measure cervical range of motion (ROM). In protocol 2, 6 sensors were placed on the spinous processes of T1, T4, T8, T12, L3, and S1 to measure TL regional ROM. Intraclass correlation coefficients were used to evaluate the repeatability of movement, whereas SEM was used to define the extent of error. Ranges of motion were demonstrated in flexion extension, right-left lateral flexion, and right-left rotation of the head-cervical, upper thoracic, middle thoracic, lower thoracic, upper lumbar, and lower lumbar. RESULTS:The intraclass correlation coefficient values, for all regions, were found to be high, ranging from 0.88 to 0.99 for all movements, and regions of the spine and SEM values ranged from 0.4° to 5.2°. Multiregional spine ROM ranged from 3° in the upper thoracic and mid-thoracic during flexion and 80° at head cervical during right rotation. CONCLUSION:The described methodology was reliable for assessing regional spinal ROM across multiple spinal regions while providing the relative motions of different segments of the TL spine.

BackgroundIt is commonplace for clinicians to measure range of motion (ROM) in the assessment of the lumbar spine. Traditional single ‘joint’ models afford measuring only a limited number of regions along the spine and may, therefore, over-simplify the description of movement. It remains to be determined if additional, useful information can be gleaned by considering the traditional ‘lumbar region’ as two regions.ObjectiveThe aim of this study was to determine whether modelling the lumbar spine as two separate regions (i.e. upper and lower), yields a different understanding of spinal movement relative to hip motion, than a traditional single-joint model. This study is unique in adopting this approach to evaluate a range of everyday tasks.MethodLumbar spine motion was measured both by being considered as a whole region (S1 to T12), and where the lumbar spine was modelled as two regions (the upper (L3-T12) and lower (S1-L3)).ResultsA significant difference was evident between the relative contribution from the lower and upper spine across all movements, with the lower lumbar spine consistently contributing on average 63% of the total ROM. A significant difference was also evident between the whole lumbar spine-hip ratio, and the lower lumbar spine-hip ratio, for the movement of lifting only. The lower lumbar spine achieved greater velocity for all tasks, when compared to the upper lumbar spine.ConclusionThis study has consistently demonstrated differences in the contribution of the upper and lower spinal regions across a range of everyday tasks; hence, it would appear that greater focus should be given to performing more detailed assessments to fully appreciate spinal movement.

OBJECTIVE:The purpose of this study was to explore the relationship between the kinematic profiles of flexion of the upper lumbar and lower lumbar (LL) spine and hip and 3 sagittally dominant functional tasks (lifting, stand-to-sit, and sit-to-stand). METHODS:Fifty-three participants were recruited for this study. Four sensors were attached to the skin over the S1, L3, T12, and lateral thigh. Relative angles between adjacent sensors were used to quantify the motion for the hip, LL, and upper lumbar spine. Pearson correlation coefficients were used to explore the relationship between the movements and more functional tasks. One-way analysis of variance was used to determine the significance of differences between the variables. RESULTS:Flexion resulted in a greater or similar range of motion (ROM) to the other tasks investigated for both spinal regions but less ROM for the hip. Strong correlations for ROM are reported between forward flexion tasks and lifting for the LL spine (r = 0.83) and all regions during stand-to-sit and sit-to-stand (r = 0.70-0.73). No tasks were strongly correlated for velocity (r = 0.03-0.55). CONCLUSION:Strong correlations were only evident for the LL spine ROM between lifting and flexion; all other tasks afforded moderate or weak correlations. This study suggests that sagittal tasks use different lumbar-hip kinematics and place different demands on the lumbar spine and hip.

BACKGROUND AND OBJECTIVES:Lifting presents a significant risk for the development of low back pain. It is not known what effect lifting from a supermarket shopping trolley has on sagittal spinal curvature. The aim of this study is to determine the effect of lifting from a shopping trolley on sagittal spinal curvature.METHODS:Fifteen female subjects (height 1.67 ± 0.04 m, weight 64.3 ± 5.0 kg) completed lifts of 9 kg from a shopping trolley and a surface matched for height whilst sagittal spinal curvature was measured using Qualysis motion analysis system. Seven retro-reflective markers were placed along spine with angle between three markers representing regional curvature. No constraints on lifting technique were instigated.RESULTS:Results demonstrate no difference in sagittal range of motion or spinal curvature across the two lifts. A small but significant difference in knee flexion angle was observed. These results demonstrate that the chosen lifting strategy was not influenced by the constraint imposed by the shopping trolley. Furthermore the function of knee flexion did not result in change in sagittal curvature during the lifts.CONCLUSION:Lifting from a shopping trolley has no effect of sagittal spinal curvature.

Bicycle helmets are designed to attenuate forces and accelerations experienced by the head during cycling accidents. An essential element of bicycle helmet design is, therefore, the appropriate manufacturing of energy dissipating components. The focus of this study was to evaluate the feasibility of using elastomeric lattice-based structures (Duraform® Flex), manufactured via a laser sintering (LS) process, as the energy dissipating inner liner of the bicycle helmet. This study is presented in two sections; the optimisation of the LS process capabilities for the manufacture of lattices based structures and an evaluation of the effects of lattice structure density on helmet impact kinematics. Through the fabrication and testing of tensile and compressive specimens, each process parameter (laser power, scanning exposure, build temperature and part orientation) was optimised to maximise compressive strength. The energy dissipating characteristics of helmet lattice structures, made from this optimised material, were evaluated during simulated helmeted headform impact tests. Reduced accelerations and increased pulse durations were reported for decreased lattice structure densities, demonstrating improved energy dissipating characteristics for this novel technique. This study demonstrates that lattice-based inner liners, manufactured via additive manufacturing processes, have exciting potential towards improving bicycle helmet safety.